It is proposed: 1) to measure the metabolic rate in a variety of cells and parts of cells in the nervous system by the rate of change in the major components of the energy reserve (ATP, P-creatine, glucose and glycogen) when the blood supply is cut off. This will be done under conditions of normal and altered neuronal activity. 2) To measure the local concentrations of a larger group of metabolites in different parts of the cell in the hopes of clarifying certain problems of metabolic control. 3) To measure the distribution of a variety of enzymes between nucleus and cytoplasm of single large cell bodies, and between axon and axon sheath.